Moments Refresher

What is the definition of a moment?

• The product of mass and acceleration

• The product of force and the perpendicular distance from a pivot

• The rate of change of velocity

• The force required to rotate an object

Which of the following conditions must be true for an object to be in equilibrium?

• The object must be stationary.

• The clockwise and anticlockwise moments must be equal, and the resultant force must be zero.

• The object must have zero velocity.

• The object must rotate.

A 10 N force acts 0.5 m from a pivot. What is the moment of the force?

• 20 Nm

• 5 Nm

• 10 Nm

• 15 Nm

A seesaw is balanced. A child weighing 300 N sits 2 m from the pivot. What force is required on the opposite side, 1.5 m from the pivot, to balance the seesaw?

• 200 N

• 300 N

• 400 N

• 450 N

A uniform beam weighs 500 N and is 4 m long. It is supported at the 1 m and 3 m marks. What is the reaction force at each support?

• 100 N and 400 N

• 250 N and 250 N

• 500 N and 0 N

• 200 N and 300 N

What happens if the resultant moment on an object is not zero?

• The object remains stationary.

• The object will rotate.

• The object will accelerate in a straight line.

• The object will move upwards.

A mechanic uses a spanner 0.3 m long to apply a force of 200 N to a bolt. What is the maximum torque they can produce?

• 60 Nm

• 600 Nm

• 6 Nm

• 0.6 Nm

What is the unit of a moment?

• N/m

• Nm

• J

• Kg m/s

What is the purpose of a lever in terms of moments?

• To reduce the effort force needed to move an object

• To eliminate all forces acting on an object

• To increase the weight of an object

• To decrease the torque on an object

A force of 50 N acts at an angle of 60° to a lever arm 0.2 m from the pivot. What is the effective moment of the force?

• 5 Nm

• 8.66 Nm

• 10 Nm

• 4.33 Nm